rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P20/2:b..l
rcu: (detected by 0, t=10502 jiffies, g=14513, q=118 ncpus=2)
task:rcuc/0 state:R running task stack:21240 pid:20 tgid:20 ppid:2 task_flags:0x4208040 flags:0x00080000
Call Trace:
context_switch kernel/sched/core.c:5256 [inline]
__schedule+0x1480/0x50a0 kernel/sched/core.c:6863
preempt_schedule_irq+0xb5/0x150 kernel/sched/core.c:7190
irqentry_exit+0x5d8/0x660 kernel/entry/common.c:216
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:lock_acquire+0x16c/0x340 kernel/locking/lockdep.c:5872
Code: 00 00 00 00 9c 8f 44 24 30 f7 44 24 30 00 02 00 00 0f 85 cd 00 00 00 f7 44 24 08 00 02 00 00 74 01 fb 65 48 8b 05 94 e7 14 10 <48> 3b 44 24 58 0f 85 e5 00 00 00 48 83 c4 60 5b 41 5c 41 5d 41 5e
RSP: 0018:ffffc90000197458 EFLAGS: 00000206
RAX: 2e718657d4262a00 RBX: 0000000000000000 RCX: 2e718657d4262a00
RDX: 000000003dfc96a1 RSI: ffffffff8cfe1d3a RDI: ffffffff8b3f5760
RBP: ffffffff81741f55 R08: ffffffff81741f55 R09: ffffffff8d5ae8c0
R10: ffffc90000197618 R11: ffffffff81ac4310 R12: 0000000000000002
R13: ffffffff8d5ae8c0 R14: 0000000000000000 R15: 0000000000000246
rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
rcu_read_lock include/linux/rcupdate.h:867 [inline]
class_rcu_constructor include/linux/rcupdate.h:1195 [inline]
unwind_next_frame+0xc2/0x23d0 arch/x86/kernel/unwind_orc.c:495
arch_stack_walk+0x11c/0x150 arch/x86/kernel/stacktrace.c:25
stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122
kasan_save_stack mm/kasan/common.c:56 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:77
kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584
poison_slab_object mm/kasan/common.c:252 [inline]
__kasan_slab_free+0x5c/0x80 mm/kasan/common.c:284
kasan_slab_free include/linux/kasan.h:234 [inline]
slab_free_hook mm/slub.c:2540 [inline]
slab_free mm/slub.c:6668 [inline]
kmem_cache_free+0x18f/0x8d0 mm/slub.c:6779
rcu_do_batch kernel/rcu/tree.c:2605 [inline]
rcu_core kernel/rcu/tree.c:2857 [inline]
rcu_cpu_kthread+0xc96/0x1c40 kernel/rcu/tree.c:2945
smpboot_thread_fn+0x542/0xa60 kernel/smpboot.c:160
kthread+0x711/0x8a0 kernel/kthread.c:463
ret_from_fork+0x599/0xb30 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
rcu: rcu_preempt kthread timer wakeup didn't happen for 10493 jiffies! g14513 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: Possible timer handling issue on cpu=1 timer-softirq=10864
rcu: rcu_preempt kthread starved for 10494 jiffies! g14513 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=1
rcu: Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt state:I stack:27664 pid:18 tgid:18 ppid:2 task_flags:0x208040 flags:0x00080000
Call Trace:
context_switch kernel/sched/core.c:5256 [inline]
__schedule+0x1480/0x50a0 kernel/sched/core.c:6863
__schedule_loop kernel/sched/core.c:6945 [inline]
schedule+0x165/0x360 kernel/sched/core.c:6960
schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99
rcu_gp_fqs_loop+0x301/0x1540 kernel/rcu/tree.c:2083
rcu_gp_kthread+0x99/0x390 kernel/rcu/tree.c:2285
kthread+0x711/0x8a0 kernel/kthread.c:463
ret_from_fork+0x599/0xb30 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 6480 Comm: syz.4.149 Not tainted syzkaller #0 PREEMPT_{RT,(full)}
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:mark_lock+0xa4/0x190 kernel/locking/lockdep.c:4774
Code: 0d 48 c7 c6 cc 49 ee 8c 67 48 0f b9 3a 90 31 c9 4c 89 fe 4c 89 f7 b8 01 00 00 00 85 69 60 74 10 5b 41 5c 41 5d 41 5e 41 5f 5d cc cc cc cc cc 49 89 fe 49 89 f7 e8 cb 8e ff ff 89 c1 31 c0 85
RSP: 0018:ffffc9000689f918 EFLAGS: 00000002
RAX: 0000000000000001 RBX: ffff88802c953c80 RCX: ffffffff92600b90
RDX: 0000000000000006 RSI: ffff88802c954810 RDI: ffff88802c953c80
RBP: ffffc9000689f9f0 R08: ffffffff8edb3377 R09: 1ffffffff1db666e
R10: dffffc0000000000 R11: fffffbfff1db666f R12: ffff88802c9548b0
R13: 0000000000000a02 R14: ffff88802c954810 R15: 0000000000000000
FS: 0000555581eb8500(0000) GS:ffff888126e01000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2f311ff8 CR3: 0000000029596000 CR4: 00000000003526f0
Call Trace:
mark_held_locks kernel/locking/lockdep.c:4325 [inline]
__trace_hardirqs_on_caller kernel/locking/lockdep.c:4351 [inline]
lockdep_hardirqs_on_prepare+0x191/0x290 kernel/locking/lockdep.c:4410
trace_hardirqs_on+0x28/0x40 kernel/trace/trace_preemptirq.c:78
__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:151 [inline]
_raw_spin_unlock_irqrestore+0x85/0x110 kernel/locking/spinlock.c:194
raw_spin_unlock_irqrestore_wake include/linux/sched/wake_q.h:94 [inline]
rtlock_slowlock kernel/locking/rtmutex.c:1896 [inline]
rtlock_lock kernel/locking/spinlock_rt.c:43 [inline]
__rt_spin_lock kernel/locking/spinlock_rt.c:49 [inline]
rt_spin_lock+0x16d/0x3e0 kernel/locking/spinlock_rt.c:57
spin_lock_irq include/linux/spinlock_rt.h:93 [inline]
snd_timer_close_locked+0x316/0x950 sound/core/timer.c:444
snd_timer_close+0x48/0xf0 sound/core/timer.c:476
snd_seq_timer_close+0xaa/0xf0 sound/core/seq/seq_timer.c:311
queue_delete sound/core/seq/seq_queue.c:126 [inline]
snd_seq_queue_delete+0x8d/0xf0 sound/core/seq/seq_queue.c:188
delete_seq_queue sound/core/seq/oss/seq_oss_init.c:371 [inline]
snd_seq_oss_release+0x1bc/0x2e0 sound/core/seq/oss/seq_oss_init.c:416
odev_release+0x51/0xa0 sound/core/seq/oss/seq_oss.c:141
__fput+0x45b/0xa80 fs/file_table.c:468
task_work_run+0x1d4/0x260 kernel/task_work.c:233
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
__exit_to_user_mode_loop kernel/entry/common.c:44 [inline]
exit_to_user_mode_loop+0xff/0x4f0 kernel/entry/common.c:75
__exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline]
do_syscall_64+0x2d0/0xf80 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f065224f749
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd3e680078 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007f06524a7da0 RCX: 00007f065224f749
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007f06524a7da0 R08: 000000000000081c R09: 000000173e68036f
R10: 00007f06524a7cb0 R11: 0000000000000246 R12: 00000000000338c3
R13: 00007f06524a6090 R14: ffffffffffffffff R15: 00007ffd3e680190